Abrasive articles typically comprise a substrate or backing having on a surface thereof a plurality of abrasive particles secured thereto by a binder. Such abrasive articles are referred to as "coated abrasives." In some instances, coated abrasives include a backing, a first coating layer bonded to one side of the backing (commonly referred to as a make coating), at least one layer of abrasive particles bonded to the backing using the first coating layer, and a second coating layer overlaying the abrasive particles, which is commonly referred to as a size coating. The purpose of the size coating is to reinforce retention of the abrasive particles. In some instances, a peripheral coating is applied over the size coating, which may contain grinding aids, lubricants, and the like.
Another type of coated abrasive construction includes a backing having an abrasive composite bonded to one side of a backing. The abrasive composite includes a plurality of abrasive particles dispersed throughout a binding medium. Typically, the abrasive composite is formed from a slurry.
Coated abrasive articles. can be converted into a wide variety of different forms such as belts, discs, cones, and sheets. It is sometimes preferable to have a pressure-sensitive adhesive (PSA) coating on at least a portion of the non-abrasive side of the coated abrasive. The coated abrasive, e.g., a disc, can then be secured to a support pad and when the abrasive disc is to be replaced, it can be removed and a new abrasive disc secured to the same support pad.
One problem with packaging a plurality of coated abrasive articles each having a PSA backing is that direct contact between the abrasive surface and the PSA can facilitate transfer of the PSA to the abrasive surface, especially in the finer abrasive particle grades of coated abrasives. Consequently, this transfer may cause contamination of the abrasive coating and, therefore, the workpiece on which it is used.
Coated abrasive articles are used to abrade a wide variety of substrates, including wood, wood-like materials, plastics, fiberglass, soft metal alloys, enamel surfaces, and painted surfaces. One problem common to all of these different substrates is "loading" or clogging. Loading is the industry term that describes the phenomenon of particles from the workpiece being abraded becoming lodged in between the abrasive particles. Loading reduces the cutting ability of the abrasive article, and thus the useful life of the abrasive article is substantially reduced.